Publications

Medicine Induced Anaphylaxis - Reporting is Vital!

Key Messages

Anaphylaxis is reported most commonly with antibiotics,
muscle relaxants, and NSAIDs but can occur with most
medicines.

Allergy testing is useful to identify or confirm the
medicine responsible for anaphylaxis.

A Medic Alert bracelet should be considered in all
patients with a serious allergy to a medicine.

Please report all cases to CARM so that an alert can be
entered in the Medical Warning Syste

Anaphylaxis is a life-threatening, systemic hypersensitivity
reaction that can occur with a wide range of medicines. Healthcare
professionals are advised to report all cases of suspected or
confirmed medicine induced anaphylaxis to the Centre for Adverse
Reactions Monitoring (CARM) even if the reaction is well known.

Reporting will enable a 'Danger' to be entered against the
patient's NHI on the Medical Warning System to alert other
healthcare professionals to the patient's allergy1.

Medical Warning System

The Medical Warning System is a national alert service that is
linked to National Health Index (NHI) numbers1. CARM
enters information on serious and/or life threatening adverse
reactions into this system as either a 'Warning' or a 'Danger'.
Anaphylaxis is always entered as a 'Danger'.

Whenever the patient's NHI is accessed, the 'Danger' is
automatically highlighted to ensure that healthcare professionals
are aware of the patient's allergy. Unfortunately, although the
system is visible to DHB's, the Medical Warning System is not
currently accessible to the majority of GPs.

Reports to CARM

From 1 January 2000 until 31 December 2013, CARM received a total
of 1433 reports of anaphylactic or anaphylactoid reactions. The
majority of patients were women (63%) and most patients had made a
full recovery (>90%) by the time of reporting to CARM.

In New Zealand, anaphylaxis is most commonly reported following
the administration of antibiotics, neuromuscular blocking agents
(muscle relaxants), NSAIDs and anaesthetics (Figure 1).

Figure 1: Top 10 classes of medicines associated with
anaphylaxis in the CARM database

While the pattern of reporting in New Zealand is consistent with
that in the published literature, the proportion of reports in each
of these classes is lower than in many studies. The lower rate may
indicate that New Zealand healthcare professionals are less likely
to report cases associated with medicines that are well known to
cause anaphylaxis.

Of note, 4.5% of the reports were for anaphylaxis to antiseptics
such as chlorhexidine which may not be well recognised as a cause of
anaphylaxis2.

Anaphylaxis Terminology

The term anaphylaxis has traditionally been used to describe IgE
mediated allergic reactions and the term anaphylactoid reaction has
been used to describe non-IgE mediated reactions. However, as the
two types of reactions are not clinically distinguishable and are
treated in the same way, anaphylaxis is now used to describe both
categories of reactions.

In 2010, the World Allergy Organization divided anaphylaxis into
three categories3.

Immunologic anaphylaxis (IgE mediated or non-IgE mediated).

Non-immunologic anaphylaxis.

Idiopathic anaphylaxis.

Medicines can cause both immunologic and non-immunologic
anaphylaxis.

Diagnosis

The diagnosis of anaphylaxis can be difficult. However,
anaphylaxis is likely if the following features are present4,5.

Treatment

Intramuscular adrenaline is the core treatment for anaphylaxis.
It should be given immediately to all patients with life-threatening
clinical features. Anaphylaxis treatment algorithms should be
followed4-6.

Long term management should include patient education, referral
for allergy testing and consideration of a Medic Alert bracelet.

For further advice on the diagnosis and management of anaphylaxis
please refer to the guidelines produced by the Best Practice
Advocacy Centre (BPAC), NZ Resuscitation Council and Starship
Children's Hospital4-6.